This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
Double buffering is turned on automatically in Swing so there is nothing for you to do.
I don't really understand your application. It looks like you are trying to display a popup JFrame with the image. You should be using a JDialog as a child window. You should not be setting the size/location of the image panel. Let the layout managers do this for you.
Unless you post a SSCCE I have no more advice to offer.